Sunscreens   can offer protection from two types of ultraviolet (UV) rays  : UVB, which according to the Skin Cancer Foundation, are the chief cause of sunburn and play a key role in the development of skin cancer, and UVA, which get through the skin more deeply and are largely responsible for skin aging and wrinkling, as well as skin cancer risk. The SPF   measurement on sunscreens refers to the UVB protection level -- and the number may not mean what you think it does. SPF 15 doesn't protect you from 15% of UVB rays, just as SPF 100 doesn't protect you from 100% of the rays. In fact, as you get into the higher numbered SPF sunscreens (think: 50 and above), the difference in UVB protection is actually pretty small. Theoretically, though the increase in UVB protection with a super-high SPF sunscreen may be not worth considering, it may help, and certainly can't hurt, to use it -- that is, as long as you do so correctly. "The only _ is whether you're giving yourself a sense of false security," Dr. Gohara says. Indeed, as Dr. Wang also pointed out, when people choose increased SPFs, they may actually feel so protected by the product that they finally ignore proper sun protection. "When people use really high SPF products, they tend not to reuse, they tend to stay out in the sun much longer, and they don't use other protective measures such as clothing and hats," he says. Regardless of any increase in protection that a high SPF may or may not offer, one thing is certain: It doesn't give your body a free pass from sunburns, aging, or cancers, and it doesn't protect you from those things for any greater length of time than the lower SPF options. Both Dr. Wang and Dr. Gohara emphasized that, no matter what the SPF is, it's important to reapply your sunscreen every two hours. Why are we advised to reapply our sunscreen every two hours? A) We choose too low SPF products. B) The higher SPF can make us stay outside longer. C) Clothing and hats are not enough for sun protection. D) It can't completely protect us from aging, sunburns or cancers.
D


Feeling tired? Under too much stress? Well, you may want to try Yoga . It's what more and more people have been turning to to release the trouble of modern life. Practically unheard of in the West until 50 years ago, Yoga has become one of the most popular health trends around the world, including prefix = st1 /China. If you search for Yoga on line in Chinese, lots of pages are there to see, most of which are main pages of Yoga clubs. In order to keep fit and lose weight, many girls spend more than 1000 yuan taking part in Yoga classes every month. However, are you really ready for it? There are several things you need to know before you really take it. First, do not force your body too much. Yoga has many difficult poses. They are beautiful and worth boasting if you could finish them. But if you force yourself to do as exactly as an experienced Yoga teacher does, you may hurt your body, instead of strengthening it. Do you remember you original purpose for playing Yoga? It is self -building, not competing.  Second, do some research about the Yoga class that you are to registering. Yoga is new in Chinaand there are not so many certificated well-trained Yoga teachers. Some not well organized clubs just find someone learn a little Yoga and certificate them. But be aware, a non- _ teacher might wrongly guide you and you could not benefit from the classes much except that they force you to exercise your body a bit. Considering about the large amount of money you invest in it, it's worth and reasonable to make sure the teachers in the club are qualified before you join.        Third, it would be better to learn something about nutrition when you practice Yoga. In the very beginning, Yoga was part of the Vedas, bible of the traditional Indian philosophy. So it could be regarded as a kind of lifestyle. When you have decided to care for your body, why not feed it properly? In fact, good clubs have their own nutritionists.        Anyhow, make sure you are ready before you act. The fashion may change quickly. But what... The author's main purpose in writing the passage is to_. A) tell people how to relax themselves B) let people know more about Yoga C) give people some advice on taking part in Yoga classes D) tell peoples Yoga has gained its popularity in China
C


The economy has developed a lot while the Internet is still not fully used in China. A study shows that about two-thirds of typical Chinese Internet users use the computer for news, often entertainment-related, or for online games, music or movies, all can be downloaded for free. Most prefers messages to e-mail, seldom makes online shopping at all. Although they are now depending on the Internet more often than before to communicate with others who have the same professions, hobbies and political interests, online shopping still remains unpopular in China. Three-quarters of users surveyed have never bought anything over the Internet, and only 10 percent do shopping even once a month. Among those who do buy online, most pay for entertainment while others buy phone cards, or computer hardware or software. "Many people don't trust the quality of goods bought online," the researcher said, "If they buy it in a store and don't like it, they can easily bring it back." The survey was done in Beijing, Shanghai, Guangzhou, Chengdu and Changsha. Results do not necessarily project countrywide because Internet use in the countryside is lower than in cities. The study showed that the typical netizens   in the five cities are richer and more highly educated. Males make up two-thirds of the group, and more than 80 percent of users are under 24.Surprisingly, with the ages increase, the percentage decreases. China has more than 200 million people online, however, forty-two percent say they do not use search engines. Others seek entertainment news, as well as information useful for work or study on line. Baidu. com was used by half of those surveyed, compared with a quarter for Google, the leading search engine in the United States. Online purchases still remain unpopular in China mainly because   _  . A) many people don't trust the quality of online goods because it is more difficult for sales returns B) most people haven't got computers C) people can't have a look at the goods D) goods bought online are of low quality

A